1. Field
One embodiment of the invention relates to a moving image decoding apparatus and a moving image decoding method each decoding a compressed moving image stream, applicable in a data reproducing apparatus and a data recording and reproducing apparatus such as a DVD player, a DVD recorder, and so on.
2. Description of the Related Art
Conventionally, there have been a data reproducing apparatus and a data recording and reproducing apparatus each capable of recording or reproducing video and sound as digital data. As these kinds of apparatuses, a DVD player and a DVD recorder both using a DVD (digital versatile disk) as a recording medium are widely used, the DVD player reading digital data recorded on the recording medium to reproduce video and sound, and the DVD recorder capable of recording digital data on the recording medium and reading digital data recorded on the recording medium to reproduce video and sound.
In such a DVD player and a DVD recorder, a decoder (decoding apparatus) is provided for decoding a moving image stream compression coded by a moving image coding system such as MPEG 2, MPEG 4, or the like. For a software decoder in which the decoder performs decoding by software, the compression coded moving image stream can be decoded by processing of a processor (CPU: Central Processing Unit) without providing dedicated hardware.
On the other hand, when decoding the compression coded moving image stream by the coding system such as MPEG 2, MPEG 4 or the like, there occurs noise typical to the coding system, such as block noise or edge noise because the image processing is performed on a block basis. Hence, a moving image reproducing apparatus has been conventionally known in which a post filter is located for removing those noises. For example, Japanese Patent Publication (KOKAI) No. 2001-245294 discloses a moving image reproducing apparatus in which filtering performed by the post filter (post filtering) on a decoded moving image signal is changed based on a reproduction status of the moving image signal to reduce time required for the post filtering so as to prevent occurrence of frame omission.